Transmission mechanism for engine starters and the like



Jan. 4, 1949. s. GILBERT 2,458,070

TRANSMISSION MECHANISM FOR ENGINE v STARTERS AND THE LIKE Filed Ju1y30, 1947 2 Sheets-Sheet 1 IN V EN TOR.

5H/77UEL E/L BER T s. GILBERT TRANSMISSION MECHANISM FOR ENGINE Jan. 4, 1949.

STARTERS AND THE LIKE 2 Sheets-Sheet 2 Filed July so. 1947 I Y INVENTOR. 5fi/77UEL EILBEHT Mam Patented Jan. 4, 1949 TRANSMISSION MECHANISM FOR ENGINE STARTERS AND THE LIKE Samuel Gilbert, Cedar Grove, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application July 30, 1947, Serial No. 764,761

4 Claims.

The present invention relates to transmission mechanisms, and particularly to a mechanism, in which an output member is adapted to be uperatively connected to, and disconnected from, an element to be driven, as in an engine starter having an output jaw for cooperation with an engine jaw.

An object of the invention is to provide novel means which, after the aforesaid operative connection is effected, is responsive to a predetermined speed of driving means for the output member, to transmit driving movement of the driving means to the element to be driven.

Another object is to apply the principle of the above stated object to a, starter having inertia means as a driving means, in response to the attainment of a predetermined speed of which the operative connection is effected.

Another object is to provide a mechanism of the above-indicated character which is simple and durable in construction, economical to manufacture, and effective in its operation.

Further objects of the invention are to simplify the starting technique of aircaft engines, eliminate guess work, as in timing the speed of an inertia member, and avoid the requirement for solenoids and other exterior controls.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example,

In the drawing:

Figure 1 is a side view, generally in section, but having parts in elevation, of an engine starter embodying one form of the invention; and

Figure 2 is a detail view taken substantially along the line 2--2 of Figure 1.

As shown in Figure 1, which illustrates only so much of the structure, as believed necessary to an understanding of the invention, the device comprises an engine starter housing I comprising an end baffleIZ, a portion I4, and a portion I6 secured to the portion I4 and supporting a motor housing I8. The housing I0 is adapted to be mounted by studs 20 on an engine crank case 22, which studs 20 extend through a flange 24 on the portion I4 and through a flange 26 on the baffle I2 into the case 22.

A rotatable motor armature element 28 has a shaft 30, journaled'by a bearing 32 in a wall 34 of the housing portion I B, and fixed to an orbital gear 36 enclosing planet gears 38 supported by a partition 40 of the housing portion I6 and meshing with the gear 36 and a sun gear 42 on the partition 40. The latter has a tubular shaft 44, loosely surrounding a reduced portion 46 of the shaft 30, and itself surrounded by a sleeve 48 of a flywheel 50.

The partition 40 has a sleeve 52 telescoping the sleeve 48 and enclosing bearings 54 between the sleeves. A nut 56 maintains the flywheel and the bearings 54 in position.

The portion 46 of the shaft 30 terminates, at the left as shown, in a portion 58 of further reduced diameter, and has a bearing 59 which supports a carrier 60 for planet gears 62 meshing with an orbital gear 64 and with a sun gear 66 keyed to the portion 58. The orbital gear 64 has a sleeve-like sun gear portion 68 journaled, as by needle bearings, on a hollow shaft I2 aligned with the shaft 30,

The sun gear portion 68 meshes with planet gears I4, which mesh with an orbital gear I6 on the housing portion I4. The planet gears 14 are mounted on a carrier 82 also having a sleeve-like sun gear 84 journaled about the shaft I2 and meshing with planet gears 88, which engage a second orbital gear 88 on the housing I4 and are carried on an end wall 90 of a barrel 92 journaled as by bearings 94 and 96 in the housing portion I4. Aspline nut 98, in the barrel 92, is connected to the latter by a torque limiting friction disc pack I00 having interlayered discs fixed to the nut 98 and the barrel 92, respectively, and axially biased together, as by springs I02 held in adjusted relation to each other, as by a ring nut I04 threaded in the opposite end of the barrel 92.

A screw shaft I06, having long lead screw thread relation to the nut 98 therein, has an axially slidable spline connection I08 to a starter clutch jaw member 0, which is adapted to engage an engine jaw clutch element H2.

The jaw H0 and the screw shaft I06 are connected, in this instance, by a mesh rod II4 having a head H5 and extending through an aperture in the jaw IIO, which aperture is closed by a seal II6 biased against the jaw IIO by a spring I I8 extending into the screw shaft I06.

The screw shaft I06 is limited in its axial movement to the right. as viewed in the drawing, by engagement with the barrel end Wall 90 and, in its axial movement, to the left, by engagement of a usual shoulder on the screw shaft I06 with a shoulder on the spline nut 98. A friction and seal structure I01, not germane to the present invention, cooperates between the baflle I2 and the jaw member II 0.

The invention, for use in combination with the above-described structure. comprises a brake III including an internal brake drum portion I20 of the housing I4 enclosing brake shoes I22 carried by a cam I24 which constitutes part of the carrier 60. The shoes I22 are axially held to the cam I24, as by side plates or rings I26 secured to the carrier 60, as by bolts or rivets I25. The shoes I22 are normally radially held in brake release position, as by garter springs I28 in grooves of the shoes maintaining the springs out of contact with the braking surface of the drum I20. The shoes I22, which aremounted on rollers I30 011 the cam I24, have shoulders I32 engaging shoulders I34 of the cam to limit the one and the same backward, radially inward or brake release movement of the shoes.- The braking movement of the shoes, in this instance, is such that the shoulders I 32 and I34 separate in response to predetermined counterclockwise rota tion of the cam I24, with the result that the eiiective radius of each shoe from the axis of the drum I 20 is increased, against the action of the'springs I28, until the shoes effectively grip the drum I20.

In operation, when the motor armature 28 is energized, rotation of the shaft 30 is transmitted idirectl y-tothe sun gear 66, and indirectly, or

through the step-up:gears"36,' 38 and 42, to the lflywheelz-Eii.

While the flywheel 50 is thus being brought up to speed, and before attaining a predetermined speed, the rotation of the various gears to the leftof the carrier 60 is *suificient such that the screw'-1shaft I08"and the jaw I I0 are advanced aXiatly: to'the left. In the latter movement, the screwi shaft l'ilfi iactsithrough the spring M8 to cause the'jaw M0 to engage the jaw H2, upon which *a-ctionjtherrotation of the orbital gear 64 is stopped, and the planet carrier 60 andits planets62 continue torrotate. s' The engagement, at

this 'ti'me,1o'f lthestart'er *jaw-I'IIl to the engine jaw 5-! His accomplished without shock loading, or. at 'zero speedrzero. torque.

W hen the flywheel 50 :attains its predetermined speed,vw-hich in'this instance is effected in about twelve esecondspthe shoes 122 overcome the springs i528 to iengage the brake drum I20, thus stopping rotation :of the" carrier 60, and causing thesun'gear 06 to rotate the planets'fiil and the onbitalrsgear "fi4, which rotation is :transmitted in ar-nsual manner through the remaining gears to the jawfI I0.

At themomentthe shoes I22 of the brake ill gripithezdrum :I 2 0, all of the stored energy of the flywheel 5c, the:armature 28 an-dother of the rotating parts, is transmitted to the engine jaw M2,; and :energization of the motor is continued until the engine starts.

-,-A I currentinertia starter, of prior practice, employs atwo-positionswitch, oneposition for acceleration, and the -other .for meshing the starter flaw, which system usually: requires the employment of a meshing solenoid, and renders it lpossible toaoverspeedwthe flywheel, with resultant excessive battery current consumption and high stresses -on-all mechanical parts.

Unders-peeding the flywheel does not give consistantstarting and :is undesirable in other Ways. By the present inventiomall of the disadvantagesrof the current inertia starter of prior practice includ-ing those above-setforth, are avoided and aanovel: and useful starter provided which is a-distinct advance in its field.

Although only oneembodiment of the inven tion has been illustrated and, described, various changes in theiorm andrelative arrangements of the :parts may be made to suit requirements.

--What is claimed is:

1 QAn engine starter, transmission mechanism com-prisingv a motor, .aflywheel, an engine-engaging' member, means responsive to rotation of said motor to move said member while substantially torque free to engine-engaging position, includingaplanetary gear train having an orbital elementxwhichbecause of said torque free condition is brought to a stop by said member when the latter reaches said positionand a planet carrier which continues to rotate with said motor, means drivably connecting said motor and flywheel, and means responsive to a predetermined speed of said"iiywheehafter said member reaches said i engine engaging position for stopping rotation of said carrier to cause the rotation of said motor and flywheel to betransmitted to said engineengagingmember through the intermediary of said orbital element.

.2; Anrenginestarter transmission mechanism comprising an engine engaging member, rotatable driving means, means responsive to rotation of said driving means to move said member while substantial-1y torque'free toengine engaging position, including-a planetary gear train having an orbital element which because of said torque free condition is brought to a stop by said member when the latter reaches said position and a planet carrier which-continues to rotate with said driving means, and meansresponsive to a predetermined speed of said driving means aftersaid member reaches said -engine-engaging position for stopping rotation of said carrier to cause the rotation of said driving meansto'be transmitted to said engine-engaging member through the intermediary of said orbita1-element.

3. A transmission mechanism 1 comprising a driving membergrotatable driving means, means responsive to rotation ofsaid'driving means to move said member while substantially torque free to position operativelyconnected to a driven elementyincluding a planetary gear train having L- an orbital elementvvhich because of said torque free condition is brought to a stop by said member when the latter reaches-said-position and a planet carrier which 'continues'to rotate with said driving means, andmeans responsive to a predetermined speed-of said, driving means 'after said member reaches said positionfor stopping rotation of said carrier to cause the rotation of said driving means to'ioe transmitted to said member through theintermediary of said orbita1 gear,

4. A transmission mechanism comprising a driving member, driving means, means responsive to movement-of said driving-means to move said member while substantiallytorque free to'position operatively related to a drivenelement, including a first-element 'which' because of said torque free-condition is brought to'a stop by said member when the latter attains said operative relation and a second-element which continues to move with said driving means; and means responsive to a predetermined'speedof said driving means-after-said'mernber attains said relation for stopping movement of :said second element to cause the movement of said driving means to be transmitted tosaid "member through the inter mediary ofsaid firsttelement. i

SAMUEL GILBERT.

1 :REFERENGES CITED The following "references-areof;record in the file of this patent:

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